First Step: Prepare the MarinadeCombine juice from 2 limes, salt, black pepper, chili powder (if using), chopped onion, chopped cilantro, and 1 tablespoon olive oil in a plastic zip-top bag. Add the flank steak, seal tightly, and refrigerate for at least 8 hours or overnight to enhance flavor and tenderize the meat.

Second Step: Prepare Cooking Tools and TortillasPreheat your grill, grill pan, or oven broiler. If unavailable, a cast iron skillet works perfectly over medium heat with 1 tablespoon olive oil. At the same time, prepare your tortillas by toasting them lightly over an open flame, a dry skillet, or in the oven until warm and slightly charred. Alternatively, wash and dry Romaine lettuce leaves for low-carb taco wraps.

Third Step: Cook the SteakRemove steak from marinade and place on preheated grill or skillet. Cook for 4 to 6 minutes per side until desired doneness (about 130°F for medium-rare, 145°F for medium). Avoid moving the steak too much to develop a good sear.

Fourth Step: Rest and Slice the SteakOnce cooked, transfer steak to a cutting board and cover loosely with foil to rest for 5 minutes to retain juices. Then slice the steak thinly against the grain into 1/8- to 1-inch strips. Optionally, warm the sliced steak briefly with remaining oil or marinade juices to keep it moist and flavorful.

Fifth Step: Assemble the TacosPlace a Romaine leaf or warm tortilla on a plate. Add shredded lettuce if using. Layer with steak strips, shredded cheese if desired, and your choice of salsa or fresh mango salsa. Drizzle with spicy cilantro lime crema if preferred. Garnish with extra chopped cilantro, green onions, and a squeeze of fresh lime.

Final Step: Serve and EnjoyServe tacos immediately to enjoy the bright, tender, and fresh flavors. Pair with side dishes like black beans, Mexican street corn, or a refreshing salad for a complete meal. For dietary swaps, use plant-based proteins or lettuce wraps and adjust toppings accordingly.